1. How far away from a long straight wire is the magnetic field strength 1.6 x 10-2 T? The current through the wire is 14A.
2. Lightning strikes a solid iron flag pole which has a resistance of 2.0 x 10^-4 ohms. The potential difference between the top and bottom of the pole is 4.2 x 10^4 V. The electrons are flowing up the pole. What will be the magnitude and direction of the magnetic field 0.72m north of the pole?